I guess the degree of difficulty depends on how technical you are (I am absolutely not technical), but here are the directions by Simsample from Mod the Sims:
I'm very interested in this mod, and I've been looking at it for a while now. But I can't make head nor tail of it... anyone explain it to me in English?
So so easy!
Download the resource file Simsample has isolated, and extracted for us.
Open your .world file in s3pe
Import the new resource file, and save!
Bingo! Bango! Bongo! You got yourself a city!
Here are step by step instructions for those of you who have never used s3pe;
Please read Simsamples thread also
Get s3pe here; s3pe Package Editor
Download the resource file. Simsamples City Resource File
Okay, now you've downloaded s3pe, and the City Resource File. Put it where you can find it. I made a folder for it and put it on my desktop.
Open up S3pe, click on "File" on the bar at the top, click on "Open", and find your .world file you wish to add these files to.
They should be in;
Sims 3 Create a World
It should look like this, I'm opening up my WhovilleBeta;
Make sure you click the "All Files" option, or your .world file won't show up.
Once you open it up, this is what it will look like;
Now, just click on the "Resource" tab on the top bar, Click on "import", and "from file". Find your City Resource File, and click on it;
Now just highlight the file, and click "Open". This is what you'll get. Just click "import", and then click on "file" on the top bar again, and "Save".
Put it wherever you like, Conorsim - your desktop would be a good place. Then when you go to resource>Import>From file, you need to go to where you saved the resource (i.e, the desktop).
Thanks for the compliment- but I'm neither a genius or a 'he'! I just used a process of elimination to find this.
You need to find where that downloaded to- usually your documents folder, or downloads folder, or the desktop.
That window is just the Firefox download window (a list of what you have downloaded).
If you can't find the file, go to Tools> Options> General in Firefox, and it will show you the location which it downloads to.